Method and apparatus for electron tubes

ABSTRACT

Method and apparatus for accomplishing the getter treatment in an electron tube which has a small volume and wherein the getter holder and material is mounted in the tip-off tube through which the envelope of the electron tube is evacuated thus utilizing the volume of the getter tube rather than the volume of the electron tube to contain the getter holder and the getter material. The method and apparatus is particularly useful with indicator display tubes which utilize conductive segments of the cathodes and anodes mounted in a common plane and which are covered by a cover envelope such that the volume within the tube is relatively small. The air is removed from the tube through the tip-off tube and the ionized gas is inserted into the tube through the tip-off tube and the getter treatment is performed in the tip-off tube so as to absorb molecules of the non-noble and residual gases within the electron tube.

United States Patent 1191 Yoshitoshi et al.

[ METHOD AND APPARATUS FOR ELECTRON TUBES [75] Inventors: Araki Yoshitoshi, Yokohama; Yzuru Yanagisawa, Fujisawa; Akira Nakayama, Tokyo, all of Japan [73] Assignee: Sony Corporation, Tokyo, Japan [22] Filed: Sept. 7, 1971 [21] Appl. No.: 178,089

[30] Foreign Application Priority Data Hunter 3l3/l77 X 1 Jan. 8, 1974 R27,273 1/1972 Kupsky. 313/1095 3,558,961 l/l97l Palsha....; 313/174 3,558,957 l/l971 Fehnel 313/174 Primary ExaminerAlfred L. Y Brody Att0rneyCarlton Hill et al.

[5 7 ABSTRACT Method and apparatus for accomplishing the getter treatment in an electron tube which has a small volume and wherein the getter holder and material is mounted in the tip-off tube through which the envelope of the electron tube is evacuated thus utilizing the volume of the getter tube rather than the volume of the electron tube to contain the getter holder and the getter material. The method and apparatus is particularly useful with indicator display tubes which utilize conductive segments of the 'cathodes and anodes mounted in a common plane and which are covered by a cover envelope such that the volume within the tube is relatively small. The air is removed from the tube through the tip-off tube and the ionized gas is inserted into the tube through the tip-off tube and the getter treatment is performed in the tip-off tube so as to absorb molecules of the non-noble and residual gases Within the electron tube.

4 Claims, 13 Drawing Figures PATENTEDJAR 8 m4 SHEET 2 OF 3 5 A M EK M vAw O m ww AMKA A m flu W; N Z1 Y wn METHOD AND APPARATUS FOR ELECTRON TUBES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to electron tubes and in particular toa novel method and apparatus of such tubes. 1

2. Description of the Prior Art Electron tubes with indicator display tubes which include a plurality of indicator units that are mounted inside a transparent glass envelope and are utilized for displaying numerals, symbols, letters and the like, have been commercially available and, for example, such indicators have been used with electric counters and other indicating means. The so-called Nixie tube includes an anode electrode and a plurality of cathode electrodes which are aligned in a stack one above the other such that selected cathode elements may be energized so that an observer sees a selected numeral or letter. Glow indicator tubes are known which utilize cathode segments mounted in a common plane such as, for example, those disclosed in US. Pat. No. 3,418,509. Another type of structure is that disclosed in U.S. Pat. No. 3,588,571, assigned to the same assignee as the present invention.

In indicator tubes of these types, according to the prior art, generally a getter treatment is performed to absorb molecules of the non-noble residual gases within the tube. For this purpose a getter receiving means is mounted in the tube in which the getter material as, for example, magnesium or barium, is mounted. The getter receiving means requires a substantial volume and this has made it difficult to produce a small indicator tube.

SUMMARY OF THE INVENTION The present invention comprises a method and apparatus for electron tube wherein a tip-off tube is mounted on a glass envelope of the tube to exhaust the air from the envelope and to insert an ionizing gas into the envelope. A getter means is mounted in the tip-off tube and the gettering is performed in said tip-off tube so as to absorb molecules of the non-noble residual gases within the envelope.

Thus it is an object of the presentinvention to provide an improved electron tube.

It is a further object of this invention to provide a flat electron tube of small volume for use with an indicator display tube.

. It is a further object of this invention to provide an electron tube for use with an indicator display tube in which a plurality of indicator units are formed on an insulating layer and which may be easily read.

It is a further object of this invention to provide an electron tube in which a tip-off tube is connected to the envelope of the tube for exhausting the air from the tube and to insert an ionizing gas into the tube.

It is a further object of this invention to provide an electron tube for use with an indicator display tube in which a getter is mounted in a tip-off tube mounted on the tube envelope and wherein gettering is performed in said tip-off tube thus allowing the volume in the display tube to be substantially reduced.

A further object of the invention is to provide an electron tube for use with an indicator display tube and in which a plurality of indicator units are mounted in the tube and wherein said units may be designed to be as small as possible.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain prferred embodiments thereof taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a cover plate of the electron tube of this invention;

FIG. 2 is a plan view of the glass backing plate of the invention;

FIG. 3 is a sectional view taken on line III-III of FIG.

FIG. 4 is a sectional view taken on line lV-IV of FIG. 2;

FIG. 5 is a plan view of the backing plate illustrated in FIG. 2 with a plurality of interconnecting leads formed thereon;

FIG. 6 is a plan view of the backing plate of FIG. 5 with an insulating layer formed over the interconnecting leads;

FIG. 7 is a plan view of the backing plate of FIG. 6 with a plurality of indicating units and selecting leads formed over the insulating layer;

FIG. 8 is a plan view of the backing plate of FIG. 7 with an insulating layer formed thereon;

FIG. 9 is a sectional view of the electron tube illustrating the cover plate attached to the backing plate;

FIG. 10 is a sectional view of the electron tube illustrating the cover plate attached to the backing plate and the tip-off tube attached to the backing plate;

FIG. 11 is an enlarged partial sectional view of a portion of the electron tube;

FIG. 12 is a sectional view of the electron tube illustrating the cover plate attached to the backing plate after the tip-off tube has been sealed; and

FIG. 13 is a plane view of the electron tube of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electron tube used in connection with this invention will be described as a gaseous glow indicator tube. The gaseous glow indicator tube is made in the following manner. An insulating base plate 2 such as illustrated in FIG. 2 has the indicator units of this invention formed thereon with the interconnecting leads and a transparent cover plate 1 is attached to the base plate 2 after the indicator units are formed. The cover plate 1 is formed with a depression or hollow portion 3 in which the indicator units are received as shown in FIG. 9.

Both of the plates 1 and 2 are made of glass and generally the base plate 2 is larger -in area than the cover plate I as may be observed by comparing FIGS. 1 and FIG. 3 is a sectional view taken on line IIIIII of FIG. 1 and illustrates the depression 3 in the cover plate 1.

FIG. 4 is a sectional view taken on line IVlV of FIG. 2.

FIG. 5 is an enlarged plan view of the base plate 2 and illustrates a plurality of interconnecting leads 10-18 which are formed on the insulating base plate 2 by suitable thin film techniques such as for example by printing. The material of the leads -18 is formed of silver as, for example, by silver paint which attaches to the glass base. It is to be particularly noted that the interconnecting leads 10-18 are grouped so that they will align with indicator units to be formed above a particular group. Thus, the interconnecting leads for the first indicator are designated by numerals 10-18 and the interconnecting leads for the second unit are designated by numerals 10'-18'.

After the interconnecting leads are formed by printed circuit techniques on the base plate 2, the plate and leads are baked to provide suitable bonding.

It is to be realized that the length of the interconnecting leads 10-18 is such that they'will be capable of interconnecting cathode and anode elements of the indicator units to suitable selecting leads as will become more apparent in the description.

FIG. 6 is a plan view of the base plate 2 in which an insulating layer 20 as, for example glass, has been deposited on the base plate 2 so as to cover a substantial portion of the interconnecting leads 10-18. The insulating layer 20 may be formed by a glass coating method by applying glass coating by spraying two or three times and then by drying it to provide it with suitable insulation coating 20 over the interconnecting leads.

Windows are formed in the insulating layer 20 at opposite ends at each of the interconnecting leads 10-18 so as to allow electrical conducting paths to be formed through the insulating layer 20 to the interconnecting leads 10-18. For example, windows 30a and 30b are formed through the insulating layer 20 at opposite ends of the interconnecting lead 10. Windows 31a and 31b are formed at opposite ends of the interconnecting lead 11 and additional windows 32a and 32b through 38a and 38b are respectively formed at opposite ends of leads 12-18. Additional windows intermediate the ends of lead 14 are formed and are designated 34c and 34d.

it is to be realized, of course, that the windows formed through the layer 20 are formed for each of the indicator units although they are only particularly numbered in FlG. 6 for the first indicator unit.

FIG. 7 illustrates the next step of the method of making the indicator unit and illustrates a plurality of indicating units 40-45 which are formed on top of the insulating layer 20.

In the next step a plurality of indicator units 40-45 (the number depending upon the desired number) are formed on the insulating layer 20 and aligned with the openings through the layer 20 so that electrical contact will be made with the interconnecting leads. Each of the indicator units comprises electrically conducting anode segments 51, 52 and 53 as well as associated plurality of cathode elements 61-68. At the same time a plurality of selecting leads 71-78 are formed on the insulating layer 20 with the leads 71-74 extending along the top of the indicator units 40-45, as shown in FIG. 7, and the selecting leads 75-78 extending along the bottom of the indicator units 40-45 as shown in FIG. 7. The anode and cathode segments and selecting leads are formed by suitable thin film techniques and are formed so as to align with the windows 30a-38a and 30b-38b so that electrical connections will be made between the selecting leads 71-78 and the anode and cathode segments. The material from which the indicator units and selecting leads are formed may be silver selecting leads 71-78 and the external leads 81-84 and 91-94 are formed at the same time by silk screen process and when the indicating units 40-45 and selecting leads 71-78 are printed on the insulating layer 20, each of the elements 61-68 and 51-53 are respectively connected to the associated selecting leads through the openings 30a-38a formed in the insulating layer 20. For example, the cathode element 62 is formed so that it aligns with opening 31b which connects it to one end of the interconnecting lead 11 and the selecting lead 74 is formed over the opening 31a so that the selecting lead 74 is connected to the cathode segment 62 through the interconnecting lead 11. Simultaneously, all of the corresponding cathode segments 62 of all of the indicator units 40-45 are connected to lead 74 through associated openings and thus all of the segments 62 of all of the indicator units are electrically connected together and to the external lead 84. Similarly, all of the cathode segments 61 are connected by interconnecting lead 10 to selecting lead 72 and to external lead 82. All of the cathode segments 63 are connected by interconnecting leads 13 to selecting lead 73 which is connected to external lead 83. Each of the cathode segments 64 are connected by interconnecting lead 12 to selecting lead 71 which is connected to external lead 81. Each of the cathode segments 65 are connected by interconnecting lead 15 to selecting lead 75 and to external lead 91. Each of the cathode segments 66 are connected by interconnecting lead 16 to selecting lead 76 which is connected to external lead 92. Each of the cathode segments 67 are connected by interconnecting lead 17 to selecting lead 77 which is connected to external lead 93. Each of the cathode segments 68 are connected by interconnecting lead 18 to selecting lead 78 which is connected to the external lead 94.

Thus, in the structure defined thus far, the associated cathode segments of all of the indicator units 40-45 are electrically connected together and thus can be electrically energized by the eight cathode selecting leads 81-84 and 91-94. The three anode segments 51, 52 and 53 of each of the indicator units 40-45 are interconnected together by the interconnecting lead 14 and a separate external lead is formed along the lower edge of the insulating plate 2 so that the anode segments of each of the indicator units can be individually energized. For example, external lead is connected to interconnecting lead 14 of the indicator unit 40 which is connected to the anode segments 51, 52 and 53 of the indicator unit 40 and the indicator unit 40 will be energized when the external lead 110 is energized with a selective pattern of the cathode segments.

Likewise the anode segments of indicator unit 41 are connected through interconnecting lead to the external anode contact 111 for indicator unit.4l. External lead 112 is connected to the associated anode segments of indicator unit 42 in a similar manner. External lead 1 13 is connected to the anode segments of indicator unit 43 and external lead 114 is connected to the anode segments of indicator unit 44. External lead 115 is connected to the anode segments of indicator unit 45.

A metal foil layer 100 of silver, for example, may be formed around the indicator units 40-45 on said insulating layer 20 at the same time that the indicating units and leads are formed with suitable windows for the indicator units as shown. A lead 101 is also formed on the insulating layer 20 and extends from the foil layer 100 to an external lead 102. Leads 101 and 102 are formed at the same time that the metal foil layer is formed and in the same manner.

In the next step, as shown in FIG. 8, a second insulating layer 210 of, for example, glass, is deposited over the selecting leads 71-78 and 101 (if used) with the indicator units left uncovered by this second insulating layer 110. In other words, the cathode segments 61-68 and the anode segments 51-53 of each of the indicator units is left uncovered by the second insulating layer 110. Also, the external leads are left uncovered by the second insulating layer 110.

Next, as shown in FIGS. 9-13, a tapered opening 121 is formed through the base plate 2 below the indicator units 40-45. A tip-off tube 122 is connected to the back of the base plate 2 surrounding the opening 121 and comprises a generally hemispherical portion 123 and a tube portion 124 as shown, for example, in FIGS. 10 and 11.

A getter means 125 is mounted in the hemispherical portion 123 of the tip-off tube 122. The getter means 125 includes a getter material receiving ring 126 to which the getter material is attached and a hanger member 127. The hanger member 127 is formed with flexible fingers which have books 128 at their ends so that when the hanger member 127 is inserted into the opening 121 of the base plate the hook portions 128 of the hanger member will lock the getter member 125 to the base plate 2 as shown in FIG. 11.

Then the air in the space between the cover plate 1 and the base plate 2 is evacuated by suitable pump or other means through the tube 124 and a suitable ionizing gas as, for example, neon or argon, is inserted through the tube 124 into the space between the cover plate 1 and the base plate 2 through the tip-off tube 122 as shown in FIG. 10. After the ionizing gas has been inserted into the space between the coverplate 1 and the base plate 2, the tip-off tube 122 is sealed in a conventional manner as shown in FIG. 12 and the tube 124 is removed leaving the hemispherical portion 123.

After the seal has been made the entire assembly is heated to l00-250 C. and simultaneously the getter treatment is performed by heating the getter means as for example by an induction heating coil at high frequencies which is placed against the hemispherical portion 123 so as to heat the getter means 125 to 1,000C. temperature for '30 seconds. This results in a getter flash which serves to absorb molecules of the nonnoble residual gases within the tube thus gettering the tube.

As shown in FIG. 11, the tip-off tube 122 may be attached to the base plate 2 around the opening 121 with a suitable cement 130 to form a so-called frit seal. The getter material may be magnesium or barium, or any of the other well-known getter materials.

Thus, an electron tube such as shown in FIG. 13 which is made very small in volume and can be very thin is produced. This is because the getter means is mounted in the tip-off tube 122 rather than in the space between the cover plate land the backing plate 2 and thus the tube does not need to be large enough to accommodate the getter means. Also, since gettering is performed in the tip-off tube hemispherical portion 123 a very small induction heater may be utilized. Also, since the getter means 125 is mounted in the tip-off tube portion 123 on the back-side of the baseplate 2, it will not interfere with observation of the indicator units. Also, the getter material will not cover the face of the indicator unit thus partially obstructing the view of the indicator units.

As shown in FIG. 12, this invention allows indicator tubes having inside thicknesses as small as 1 mm indicated by dimension 1 in FIG. 12, and outside thickness dimensions of about 5 mm indicated by dimensions d in FIG. 12. These are very thin indicator tubes and thus a very compact unit is available.

It is to be realized, of course, that the opening 121 through the base plate 2 may be formed before the indicator patterns are formed. Also, the frit seal which attaches the cover plate 1 to the base plate 2 may be formed at the same time that the frit seal attaching the tip-off tube 122 to the back of the base plate is made.

It is also to be realized that the invention is not limited to gaseous glow indicator display tubes but any other tube, as for example, fluorescent type display tubes may be constructed according to the invention.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim:

1. An electron tube for use with an alpha numeric indicator display comprising: I

a planar base plate formed with an opening extending from first to second parallel surfaces;

a least one indicator unit formed on said first surface of said base plate;

a transparent cover sealed to said base plate to form a thin envelope over said first surface with said indicator unit within and spaced closely to said first surface; I

a hemispherical cover portion'attached to said second surface of said base plate over said opening;

a noble gas contained in said envelope; and

a getter means mounted in the'space between the second surface of said base plate and said hemispherical cover portion and said getter means comprising a getter material receiving ring lying in a plane parallel to said first surface, getter material attached to said receiving ring, and a hanger member attaching said getter material receiving ring to said base plate.

2. An electron tube for use with an indicator display according to claim 1 wherein said hanger member is formed with fingers which extend through said opening and hooks formed at the ends of said fingers which engage said first surface of said base plate to attach said hanger member to said base plate.'

3. An electron tube for use with an alpha numeric indicator display comprising:

a planar plate of insulating material formed with an opening extending from first to second parallel surfaces,

a plurality of segmented cathodes formed on said first surface of said planar plate;

a plurality of cathode leads corresponding to the number of segments in each cathode electrode and respectively connected to corresponding ones of said segmented cathode electrodes;

a plurality of anode leads formed on said first surface of said plate;

a plurality of anode electrodes formed on first surface of said plate and in an associated relationship with said cathode electrodes and respectively connected to said plurality of anode leads with a separate anode lead for each anode electrode to form a plurality of alpha numeric indicator units,

a transparent cover sealed to said first surface of said insulating planar plate to form a thin envelope with said electrode structure within a noble gas with said envelope;

a hemispherical cover portion connected to the second surface of said planar plate over said opening;

a getter means mounted in the space between said hemispherical cover portion and the second surface of said planar plate and said getter means comprising a getter material receiving ring lying in a plane parallel to said first and second surfaces, getter material attached to said receiving ring, and

a hanger member attaching said getter material receiving ring to said base plate.

4. An electron tube for use with an indicator display according to claim 3 wherein said hanger member is formed with fingers which extend through said opening and hooks formed at the ends of said fingers which engage said first surface of said base plate to attach said hanger member to said base plate. 

1. An electron tube for use with an alpha numeric indicator display comprising: a planar base plate formed with an opening extending from first to second parallel surfaces; a least one indicator unit formed on said first surface of said base plate; a transparent cover sealed to said base plate to form a thin envelope over said first surface with said indicator unit within and spaced closely to said first surface; a hemispherical cover portion attached to said second surface of said base plate over said opening; a noble gas contained in said envelope; and a getter means mounted in the space between the second surface of said base plate and said hemispherical cover portion and said getter means comprising a getter material receiving ring lying in a plane parallel to said first surface, getter material attached to said receiving ring, and a hanger member attaching said getter material receiving ring to said base plate.
 2. An electron tube for use with an indicator display according to claim 1 wherein said hanger member is formed with fingers which extend through said opening and hooks formed at the ends of said fingers which engage said first surface of said base plate to attach said hanger member to said base plate.
 3. An electron tube for use with an alpha numeric indicator display comprising: a planar plate of insulating material formed with an opening extending from first to second parallel surfaces, a plurality of segmented cathodes formed on said first surface of said planar plate; a plurality of cathode leads corresponding to the number of segments in each cathode electrode and respectively connected to corresponding ones of said segmented cathode electrodes; a plurality of anode leads formed on said first surface of said plate; a plurality of anode electrodes formed on first surface of said plate and in an associated relationship with said cathode electrodes and respectively connected to said plurality of anode leads with a separate anode lead for each anode electrode to form a plurality of alpha numeric indicator units, a transparent cover sealed to said first surface of said insulating planar plate to form a thin envelope with said electrode structure within a noble gas with said envelope; a hemispherical cover portion connected to the second surface of said planar plate over said opening; a getter means mounted in the space between said hemispherical cover portion and the second surface of said planar plate and said getter means comprising a getter material receiving ring lying in a plane parallel to said first and second surfaces, getter material attached to said receiving ring, and a hanger member attaching said getter material receiving ring to said base plate.
 4. An electron tube for use with an indicator display according to claim 3 wherein said hanger member is formed with fingers which extend through said opening and hooks formed at the ends of said fingers which engage said first surface of said base plate to attach said hanger member to said base plate. 